Visible/ir camera-based multi-phase flow sensor for downhole measurements in oil pipes

ABSTRACT

Systems and methods for measuring flow velocity of a fluid mixture in a lateral section of an oil/gas well are presented. The flow velocity is measured by tracking movement of particles and/or features in the fluid mixture via visible and/or infrared imaging sensors of a camera-based flow sensor. According to another aspect, the imaging sensors detect back-reflected light by the particles and/or features, the light emitted by illuminators in the visible and/or infrared spectrum. According to yet another aspect, the particles are quantum dot illuminators injected into the fluid mixture, the flow velocity based on a time-of-flight of the quantum dots. The camera-based flow sensor may be rotatable to measure flow velocities at different angular positions of a pipe, rotation provided by rotation of an element of a mobile vessel to which the flow sensor is rigidly coupled.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to and the benefit of co-pendingU.S. provisional patent application Ser. No. 63/039,591 entitled“Infrared/Visible Optical Flow Sensor for Multi-Phase Mixtures”, filedon Jun. 16, 2020, the disclosure of which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present disclosure generally relates to systems and methods formeasuring fluid flow rate in fluid mixtures, such as, for example,mixtures of oil, water and gas found in lateral oil/gas wells.

BACKGROUND

Detailed information about physical properties (e.g., reservoir inflow)in the downhole of an oil-gas producing well, is important to helpoptimize production and field development. Inflow data points such asoil-gas-water flow rates, pressure, and temperature, for example, arekey to understanding the nature of the reservoir properties and theeffect of well drilling and completion methods. Although useful, theinflow data are not often measured in real-time, or with considerablefrequency (weekly or more frequently), along the lateral section of thewell due to technical or cost-prohibitive challenges. Instead, surfacewell-head production data (total flow rates, pressure, temperature,etc.) are measured for well performance diagnostics and for reportingpurposes.

Attempts to instrument the well for real time or at least weeklymeasurements with continuous electrical or fiber optic cables forpowering sensors to measure and deliver physical properties in thedownhole of a well have been tested and have not been cost effective.This is particularly true for shale and tight development wells thathave, for example, long laterals and multiple perforation entry pointsof their casing pipe (to contact the rock formation) which then undergohigh-pressure hydraulic fracturing to increase hydrocarbon inflows fromoil-bearing rock formations. Such harsh activities can easily damage notonly the sensors but also power and data cables in the downhole of awell.

Production-logging tools (PLTs) are used routinely within long,horizontal wells to make measurements of local pressure, temperature,composition and flow rates. PLTs, however, are provided as a service andrequire well intervention for data to be collected; the operational costand complexity limiting the frequency the data can be collected within awell.

Unconventional tight rock geologic formations may require a large numberof oil/gas wells (holes) drilled in close proximity to each other toeffectively extract the hydrocarbon contained in a field.Horizontally-drilled wells may be used in these applications since thehydrocarbon-bearing rock formations tend to exist in stratified layersaligned perpendicular to the gravity vector.

The typical vertical section of these wells can be 1-3 km below thesurface and can extend laterally (e.g., in a generally horizontaldirection) for distances of, for example, 2-3 km or even more. Oil,natural gas, and water may enter the well at many locations (productionintervals/zones open to perforations and fracturing) formed along alateral distance (e.g., 2-3 km or more) of the well with local flowrates and composition (e.g. oil/water fractions) varying due to inherentgeology and the accuracy with which the well intersects (e.g., at theproduction intervals or sections) the oil-bearing rock formations. Ingeneral, information about the performance or hydrocarbon delivery andcapacity of a well, such as, for example, flow rate, pressure, andcomposition, can practically be measured at the surface of the wellas-combined values and with little or no knowledge of individualcontributions from each of the production intervals or zones. Lack oflocal information of the inflow details of the well, at, for example,the production intervals or zones, can be a barrier to improving theefficiency of oil-gas extraction from the overall field.

Better knowledge of local interval inflow data across each or multipleentry points (e.g. physical properties such as flow rates, pressure,temperature, etc.) at the downhole of a well (e.g., along thehorizontal/lateral section of the well) may help in making betterdecisions about placement of subsequent perforation/completion intervalsfor production in a well and/or subsequent drilling of other wells inthe field.

For example, an oil production field may have a variety of drilledwells, including an unconventional horizontal oil well that extracts oilfrom shale and tight formation through a plurality of productionintervals or zones (shown as rectangles). In order to develop the field,producing the hydrocarbon-bearing rock formations, a number of wells(i.e., holes) may be drilled and spaced, for example, in the order of500 feet apart from each other. These wells are drilled and completedserially so that information may be gathered from a downhole of a firstwell, for example, and can aid in determining where to perforate thecasing and to apply hydraulic fracturing at selected intervals of theformation in a second and following well.

SUMMARY

Although the present systems and methods are described with reference towells used in the oil industry, such systems and methods may equallyapply to other industries, such as, for example, deep sea exploration orthrough-ice exploration. Furthermore, although the present systems andmethods are described with reference to oil-gas-water mixtures found inoil wells, such systems and methods may equally apply to any other fluidmixtures.

According to one embodiment the present disclosure, a system forgathering information about physical properties in a lateral section ofa well is presented, the system comprising: a mobile vessel configuredfor submersion into a fluid mixture of the lateral section of the well;and a camera-based flow sensor attached to the mobile vessel, thecamera-based flow sensor comprising: a camera system configured tocapture images in a visible spectrum and in an infrared spectrum; and anilluminator system configured to emit light in the visible spectrum andin the infrared spectrum, wherein the camera-based flow sensor isconfigured to emit light into the fluid mixture and capture images ofback-reflected light from features present in the fluid mixture.

According to a second embodiment of the present disclosure, a system forgathering information about physical properties in a lateral section ofa well is presented, the system comprising: a mobile vessel configuredfor submersion into a fluid mixture of the lateral section of the well;and a camera-based flow sensor attached to the mobile vessel, thecamera-based flow sensor comprising: a quantum dot illuminator systemcomprising a plurality of quantum dot illuminators configured to emitlight in the visible spectrum, the quantum dot illuminator systemconfigured to release a group of quantum dot illuminators of theplurality of quantum dot illuminators into the fluid mixture; and afirst camera system configured to capture a first image of light emittedby the at least one quantum dot illuminator through the fluid mixture.

According to a third embodiment of the present disclosure, acamera-based flow sensor is presented, the camera-based flow sensorcomprising: a camera system configured to capture images in a visiblespectrum and in an infrared spectrum; and an illuminator systemconfigured to emit light in the visible spectrum and in the infraredspectrum, wherein the camera-based flow sensor is configured to emitlight into a fluid mixture and capture images of back-reflected lightfrom features present in the fluid mixture.

According to a fourth embodiment of the present disclosure, acamera-based flow sensor is presented, the camera-based flow sensorcomprising: a quantum dot illuminator system comprising a plurality ofquantum dot illuminators configured to emit light in the visiblespectrum, the quantum dot illuminator system configured to release agroup of quantum dot illuminators of the plurality of quantum dotilluminators into a fluid mixture; and a camera system configured tocapture a first image of light emitted by the group of quantum dotilluminators through the fluid mixture.

According to a fifth embodiment of the present disclosure, a method formeasuring a flow velocity of a fluid mixture is presented, the methodcomprising: emitting a light into the fluid mixture; based on theemitting, capturing a sequence of consecutive images of back-reflectedlight from features present in the fluid mixture; and based on thecapturing, determining the flow velocity based on relative movement ofthe features within the sequence of consecutive images.

According to a sixth embodiment of the present disclosure, a method formeasuring a flow velocity of a fluid mixture is presented, the methodcomprising: releasing a group of quantum dot illuminators into the fluidmixture; based on the releasing, capturing a first image of lightemitted by the group of quantum dot illuminators through the fluidmixture; determining a lapsed time between the releasing and thecapturing; based on the determining, and based on a distance between arelease position of the group of quantum dot illuminators and a positionof a field of view of the first image, determining a time-of-flight ofthe group of quantum dot illuminators; and based on the determining ofthe time-of-flight, determining the flow velocity

Further aspects of the disclosure are shown in the specification,drawings and claims of the present application.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated into and constitute apart of this specification, illustrate one or more embodiments of thepresent disclosure and, together with the description of exampleembodiments, serve to explain the principles and implementations of thedisclosure.

FIG. 1 illustrates a cross sectional view of an example known oilproduction field, comprising one or more drilled wells for production ofoil and/or gas in which a mobile vessel constructed in accordance withthis disclosure may be disposed.

FIG. 2 shows a lateral section of a well of the oil production fieldshown in FIG. 1 comprising a plurality of production zones in which amobile vessel constructed in accordance with this disclosure may beused.

FIG. 3 shows an example embodiment of a mobile vessel comprising acamera-based flow sensor according to the present disclosure, the mobilevessel positioned in a lateral section of a well of the oil productionfield shown in FIG. 1 .

FIG. 4A shows a front view of the mobile vessel of FIG. 3 with thecamera-based flow sensor positioned at a first angular position.

FIG. 4B shows a front view of the vessel of FIG. 3 with the camera-basedflow sensor positioned at a second angular position.

FIG. 4C shows a camera-based flow sensor according to an embodiment ofthe present disclosure for simultaneous measurement of flow rate at aplurality of angular positions.

FIG. 5A shows details of a cross sectional front view of thecamera-based flow sensor according to an embodiment of the presentdisclosure.

FIG. 5B shows details of a cross sectional side view of the camera-basedflow sensor according to an embodiment of the present disclosure.

FIG. 6 shows a graph representative of a performance of an example CMOSimaging sensor used in the camera-based flow sensor according to thepresent disclosure.

FIG. 7 shows a block diagram according to an embodiment of the presentdisclosure of the camera-based flow sensor of FIG. 5A and FIG. 5B.

FIG. 8A shows details of a cross sectional side view of a camera-basedflow sensor according to another embodiment of the present disclosurethat is based on the camera-based flow sensor of FIG. 5A and FIG. 5B.

FIG. 8B shows details of a cross sectional side view of a camera-basedflow sensor according to another embodiment of the present disclosurethat is based on the camera-based flow sensor of FIG. 8A.

FIG. 8C shows details of a cross sectional side view of a camera-basedflow sensor according to another embodiment of the present disclosurethat is based on the camera-based flow sensor of FIG. 8B.

FIG. 9 shows a block diagram according to an embodiment of the presentdisclosure of the camera-based flow sensor of FIG. 8C.

FIG. 10A shows the mobile vessel of FIG. 3 within a casing pipe of alateral well, the camera-based flow sensor arranged in a nose of themobile vessel.

FIG. 10B shows the mobile vessel of FIG. 3 within a casing pipe of alateral well, the camera-based flow sensor arranged in a main body ofthe mobile vessel.

FIG. 10C shows an example embodiment of another mobile vessel comprisingthe camera-based flow sensor according to the present disclosure.

Like reference numbers and designations in the various drawings indicatelike elements.

Definitions

As used herein the term “flow velocity” of a fluid may refer to themotion of the fluid per unit of time and may be represented locally by acorresponding “fluid velocity vector”. As used herein, the term “flowrate” of a fluid may refer to a volume of the fluid flowing past a pointper unit of time. Therefore, considering a cross-sectional area of aflow of fluid, such as a flow of fluid through a lateral section of anoil well, the flow rate through the cross-sectional area can be providedby the flow velocity at that area.

As used herein the term “flow meter” may refer to a system that that iscalibrated to provide a precise measurement of the flow velocity basedon signals sensed by a flow sensor.

As used herein the term “infrared”, “infrared light” and “infraredemission” are synonymous and may refer to an electromagnetic radiation(EMR) with wavelengths in a range from about 780 nanometers to 1millimeter and longer than those of visible light. As used herein theterm “near infrared”, “near infrared light” and “near infrared emission”are synonymous and may refer to an electromagnetic radiation (EMR) withwavelengths in a range from about 780 nanometers to 3,000 nanometers.

As used herein the term “visible”, “visible light” and “visibleemission” are synonymous and may refer to an electromagnetic radiation(EMR) with wavelengths in a range from about 380 nanometers to about 780nanometers. Electromagnetic radiation in this range of wavelengths isvisible to the human eye.

DETAILED DESCRIPTION

As set forth above, information may be gathered from a downhole of afirst well, for example, and can aid in determining where to perforatethe casing and to apply hydraulic fracturing at selected intervals ofthe formation in a second and following well. Other useful informationthat may be collected within a well includes, by way of non-limitingexample, fluid flow rates/velocities. Certain sensors for measuring flowrates (velocity) in an oil well are based on spinners (e.g., impellers)that rotate with angular speeds as a function of incident flow rates.When considering an oil-water-gas-sand environment as provided in alateral section of a well, spinner technology is challenged primarilyfor its robustness and longevity within the environment. This includesdifficulties with calibration and survivability incited by moving partsof the spinner-based sensors in a downhole environment, especially whenconsidering operation over a length of months and/or years.

Teachings according to the present disclosure, among other technicaladvantages, solve the prior art shortcomings by providing a camera-basedflow sensor configuration that may be considered as a “solid state”solution with the ability of measuring flow velocity profiles withgreater accuracy while operating unattended for extended periods oftime. When integrated with a mobile vessel, the flow sensor according tothe present teachings may measure flow velocities of a fluid mixture ofthe downhole under a wide range of thermodynamic conditions, includingat downhole pressures greater than 5000 psi, accurately and efficiently.

According to some embodiments of the present disclosure, thecamera-based flow sensor may include a dual imaging sensor cameracapable of resolving/capturing features in the fluid mixture that emitor reflect light in the visible and/or in the near infrared spectrum.Such features may correspond to any change in contrast present in thefluid mixture which the flow sensor can detect and track with thecamera. Relative movement/position of the features in consecutivecaptured images (frames) and the rate of the capturing of the images(frame rate) allow determination of velocity of the features in thefluid mixture, and therefore of the fluid mixture (e.g., since thefeatures can be assumed in equilibrium with the fluid mixtures). Theframe rate may be selected in view of a target range of measurementvelocities.

According to some embodiments of the present disclosure, thecamera-based flow sensor can be controlled/configured for operation inthe visible and/or in the infrared spectrum. For example, in a casewhere phases present in the fluid mixture in a field of view of thecamera is not known, operation according to the visible and infraredspectrum can be multiplexed so to broaden the detection spectrum (e.g.,sequence of images/frames captured with alternated spectrum).Alternatively, the camera can be controlled for simultaneous operationaccording to the visible and infrared spectrum so to broaden thedetection spectrum and to increase resolution of the detection (e.g.,sequence of images/frames each captured with broadened spectrum). On theother hand, in a case where a phase present in the fluid mixture in thefield of view of the camera is known (e.g., via specific compositionsensors in the mobile vessel), operation of the camera can be controlledbased on an (a priori known) absorption spectrum of the phase. Forexample, while the absorption spectrum of oil includes a region of highabsorption across the visible spectrum, it includes a region of lowabsorption (e.g., increased transmission) in a wavelength range between1500 nm and 1700 nm, e.g. near 1600 nm, that is part of the nearinfrared spectrum. Accordingly, for sensing velocity in oil, the flowsensor according to the present disclosure may, in certain embodiments,be controlled to operate in the infrared spectrum.

According to some embodiments of the present disclosure, the changes incontrast detectable by the flow sensor may be based on back-reflectedlight from particles in the fluid or the fluid itself. In cases wherethe field of view of the camera includes multiple phases of the fluidmixture, the change in contrast may be based on back-reflected lightfrom the interface between two phases (e.g., where gas and oil meet orwhere oil and water meet) of the fluid mixture. According to someembodiments of the present disclosure, the back-reflected light may bebased on one or more illuminators (e.g., light sources/emitters,illumination sources/emitters) included in the flow sensor. According toan example embodiment, two illuminators may be provided: a visiblespectrum illuminator for emitting light in the visible spectrum; and aninfrared (e.g., near infrared) spectrum illuminator for emitting lightin the infrared spectrum. During operation of the camera-based flowsensor in the visible spectrum, the visible spectrum illuminator may beenabled, and during operation of the camera-based flow sensor in theinfrared spectrum, the infrared spectrum illuminator may be enabled.Each of the two illuminators may be arranged relative to the camera soto illuminate the field of view of the camera.

In some cases, the fluid mixture may include phases that includeabsorption spectra with peaks in the emission spectra of theilluminators included in the camera-based flow sensor. In other words,the fluid mixture may absorb a substantial portion of the (emitted)illumination such that no back-reflected light may be detected by theimaging sensors of the camera. It follows that according to anembodiment of the present disclosure, the flow sensor may inject lightemitting particles (e.g., quantum dot illuminators) into the fluidmixture that can emit at wavelengths outside the peaks of the absorptionspectra of the phases of the fluid mixture, and therefore can bedetected and tracked by the camera-based sensor. An emissionspectrum/wavelength of such quantum dot illuminators may be selectedbased on a quantum efficiency of either one of the two imaging sensorsused in the camera-based sensor so to increase detection efficiency.According to a nonlimiting embodiment of the present disclosure, theemission spectrum/wavelength of the quantum dot illuminators may be inthe visible spectrum. According to a nonlimiting embodiment of thepresent disclosure, the emission wavelength of the quantum dots may bein a range from 450 nm to 750 nm, corresponding to a region of highquantum efficiency of an imaging sensor represented by the graph of FIG.6 later described.

Once injected into the fluid mixture, a quantum dot illuminator, or acluster/group of quantum dot illuminators, may travel through the fluidmixture with the flow of the fluid mixture and therefore with a velocitythat corresponds to the velocity of the fluid. According to an exampleembodiment of the present disclosure, the velocity of the fluid can bedetermined by establishing a time-of-flight (TOF) of the quantum dotilluminator (or cluster/group of dots) between its position wheninjected into the fluid, to its position in (a region of) a framecaptured by the camera system. In some embodiments, and to reduceeffects of flow perturbation, the time-of-flight may be based on atravel distance of the quantum dot illuminator of 10 cm or more. Furtheraccuracy in the determination of the velocity can be provided viaprovision of one or more additional camera-based flow sensors arrangedat different distances from one another so to determine the (fluid)velocity from a plurality of time-of-flights (e.g., from injection tofirst camera, from first camera to second camera, etc.).

According to an embodiment of the present disclosure, the quantum dotsmay be particles or nanocrystals of a semiconducting material in therange of 2-10 nm in diameter. These particles can be composed of asingle material, a core material with shell of a different composition,or an alloy. Emission wavelengths of such quantum dots may be changed bymodifying their composition while keeping their size constant. Thisallows to select an emission wavelength that can be detected from thecamera-based flow sensor while reducing absorption through the fluidmixture, including in a region of a single phase (e.g., crude oil).

According to an example embodiment of the present disclosure, thequantum dots may be CdS_(x)Se_(1-x)/ZnS (CdSe core and ZnS shell)alloyed quantum dots with a size of about 6 nm. Such CdS_(x)Se_(1-x)/ZnSquantum dots may be held in suspension in Toluene contained within areservoir for injection into the fluid mixture as bubbles. An emissionwavelength of the CdS_(x)Se_(1-x)/ZnS quantum dots may be in a rangefrom 610 nm to 630 nm.

According to an example embodiment of the present disclosure, thecamera-based flow sensor can operate in: a) a reflective mode thatdetects back-reflected light from particle/features in the fluid mixtureilluminated by light emitted from the illuminators; b) a transmissivemode that detects light emitted by injected quantum dot illuminators andtransmitted through the fluid mixture, or c) a combination of a) and b).For cases wherein operation only according to the reflective mode isdesired, implementation of the camera-based flow sensor may not includesupport for storage and ejection of the quantum dot illuminators. Forcases wherein operation only according to the transmissive mode isdesired, implementation of the camera-based flow sensor can besimplified by providing a camera system with a single imaging sensor(e.g., operating in the visible spectrum) and no illuminators.

The mobile vessel described herein may be used in a number of settings,an example of which is depicted in FIG. 1 , which illustrates a crosssectional view of an example oil production field (100), comprising oneor more drilled wells (Well_1, Well_2, . . . ) for production andextraction of oil and/or gas from various regions of the field. Inparticular, as can be seen in FIG. 1 , a vertical section of the Well_1may be drilled to reach and penetrate an oil- or gas-rich shale (e.g.,rock formation), and a lateral (e.g., horizontal) section of the Well_1,which, in the example case of FIG. 1 is substantially horizontal, may bedrilled along the shale, starting from a heel section of the Well_1, andending at a toe section of the Well_1. Generally, the vertical sectionof the Well_1 may extend 1 to 3 km below the surface and the lateralsection of the Well_1 may extend for distances of, for example, 2-3 kmor more.

With continued reference to FIG. 1 , fluid mixtures, including oil,water, and/or natural gas mixtures, may enter the Well_1, for example,through open-hole or a casing of the Well_1, at production perforatedintervals/zones that may be formed in the lateral section of the Well_1.Each of such production intervals/zones may include holes and/oropenings that extract the fluid from the shale and route into the casingof the Well_1. As shown in FIG. 1 , the perforated intervals/productionzones may be separated by distances of, for example, about 100 meters(e.g., about 300 feet), and between each of the intervals (or stages)there are several clusters of perforations with closer spacing in orderto cover a lengthy lateral and extract more hydrocarbon from shale/tightformations. Since there are many production zones, the inflowcontribution for each of the intervals (or zones or clusters), such as,for example, local pressure, temperature, flow rates, and composition,may vary due to inherent geology and the accuracy with which the lateralsection of the Well_1 intersects the oil-bearing rock formations at theproduction zones.

As described above, collecting data at regions of the Well_1, forexample close to each of the production zones, can help evaluateeffectiveness of inflow contribution for each of the production zonesand further help in optimizing production (e.g., by altering theperforation/completion design). The camera-based flow sensor accordingto the present disclosure, integrated with a mobile vessel as describedherein, may be used to measure a flow velocity of the fluid in thelateral section of the Well_1, the flow velocity inferred by velocity offeatures detected and tracked by one or more cameras (e.g., imagingsensors) of the flow sensor. Because different fluids and differentphases of a fluid may include different absorption spectra, sensing ofthe flow may be based on information provided by other sensors that areplaced inside of the lateral section of the well. Data sensed by suchother sensors may include data related to, for example, pressure,temperature and composition (e.g., fraction of oil, gas, water).Furthermore, derivation of an effective fluid velocity based on velocityof the features detected and tracked by the camera-based flow sensor,may be based on a calibration routine that further takes into accountany perturbation of the flow of the fluid in a region of the field ofview of the camera-based sensor. For example, such calibration routinemay consider flow restriction (e.g., variation of an effectivecross-sectional area for the flow of the fluid) in a region of the fieldof view of the camera that may result in a higher velocity of thedetected features.

FIG. 2 shows a lateral section of a well of the oil production fieldshown in FIG. 1 comprising a plurality of production zones indicated as(Z1, Z′1, . . . , Zn, Z′n). Also shown in FIG. 2 are local fluidvelocity vectors (V_(F1), . . . , V_(Fn)) at vicinity of respectiveproduction zones. For example, the fluid velocity vector V_(F1), may beconsidered solely based on an inflow (of fluid) contribution by the lastproduction zone (Z1, Z′1) close to the toe section of the well. On theother hand, the fluid velocity vector V_(F2) may be considered based ona combination of the inflow contribution of the production zone (Z2,Z′2) combined with the inflow contribution of the last production zone(Z1, Z′ 1). In other words, a magnitude of the fluid velocity vector(V_(F1), V_(F2), . . . , V_(Fn)) along the lateral section of the wellshown in FIG. 2 may be considered as an incremental magnitude withincrements based on inflows provided by the respective production zones(Z1, Z′1, . . . , Zn, Z′n). Accordingly, a performance of each of theproduction zones (Z1, Z′1, . . . , Zn, Z′n) based on a correspondinginflow contribution may be assessed by measuring a difference between amagnitude of a fluid velocity vector before and after each productionzone. For example, a difference between a magnitude of V_(F2) and amagnitude of V_(F1) may indicate an inflow performance of the productionzone (Z2, Z′2).

When integrated with a mobile vessel, such as a mobile robot, thecamera-based flow sensor according to the present disclosure may be usedto measure the magnitude of the local fluid velocity vectors (V_(F1), .. . , V_(Fn)). This is shown in FIG. 3 , where the mobile vessel (200),including for example an element (210) and an element (220), fitted withthe camera-based flow sensor (250) according to the present teachings ispositioned downstream (e.g., towards the heel section of the well) ofthe production zone (Zk, Z′k) for measurement of a magnitude of thelocal fluid velocity vector V_(Fk). In this case, the mobile vessel(200) may be controlled to remain stationary during thegathering/sensing of corresponding measurement data and move to a nextproduction zone for a next measurement. In some embodiments, actualderivation of the magnitude of the local fluid velocity vector may beperformed either in real-time or non-real-time based on data sensed bythe camera-based flow sensor (250) which may be combined with datasensed by other sensors as described above. It should be noted that theterm “data” as used herein may relate to an ensemble of data valuesrepresentative of signals gathered/sensed by one or more sensors of, forexample, the camera-based flow sensor of the present teachings. Suchdata may be stored on local or remote memory for immediate or futureuse. In the particular case of the camera-based flow sensor of thepresent teachings, such data may include entire image frames, includingfor example, corresponding pixel data. Other data may include, forexample, image frame rate and/or injection time and detection time ofthe quantum dots for derivation of corresponding time-of-flight.

FIG. 4A shows a front view of the vessel of FIG. 3 with the camera-basedflow sensor (250) positioned at a first angular position about a centeraxis, C, of the element (220, e.g., nose) of the mobile vessel (200)shown in FIG. 3 . The center axis C may be a common axis of the elements(210) and (220) of the mobile vessel (200) as shown in FIG. 3 , or maybe an axis that is different from (e.g., parallel to) a center axis ofthe element (210, e.g., main body) of the mobile vessel. According tosome example embodiments, the elements (210) and (220) of the mobilevessel (e.g., 200 of FIG. 3 ) may include a tubular or cylindrical shapeabout the center axis C, or about a respective center axis. Also shownin FIG. 4A is a direction of the local fluid velocity vector V_(Fk)which in the example configuration of FIG. 4A is assumed (substantially)parallel to an axial direction of the lateral portion of the well, asalso shown in FIG. 3 .

According to an embodiment of the present disclosure, the camera-basedflow sensor (250) of FIG. 4A comprises a camera system (250 a) that mayinclude visible and infrared imaging sensors (250 a), and an illuminatorsystem (250 b) that may include one or more illuminators (250 b) thatemit light at wavelengths detectable by the imaging sensors. The camerasystem (250 a) and the illuminator system (250 b) may be enclosed in anenclosure/housing (250 d) that protrudes the element (220) of the mobilevessel and protects (along with element 250 c later described) theelements (250 a, 250 b) against the outside environment (e.g., wellenvironment). According to a nonlimiting embodiment of the presentdisclosure, the enclosure (250 d) may include an axis of symmetry, S,that as shown in FIG. 4A may pass through the center axis, C, of theelement (220). According to a nonlimiting embodiment of the presentdisclosure, a shape of the enclosure (250 d) may be cylindrical so toreduce perturbation of the fluid at vicinity of the camera-based flowsensor (250). Other shapes, including shapes about the axis of symmetry,S, may be envisioned, with a corresponding perturbation of the flowfactored in a calibration routine used to determine an effectivevelocity of the flow.

As shown in FIG. 4A, at an outer radial position (e.g., referenced tothe center axis, C), the enclosure (250 d) may include a window (250 c,aperture) for transmission and/or detection of light from/by the camerasystem (250 a) and/or the illuminator system (250 b). As describedabove, the combination of the enclosure (250 d) and the windows (250 c)provide an interior space for the camera system (250 a) and theilluminator system (250 b) that is sealed and protected from thedownhole environment. According to an example embodiment of the presentdisclosure, the window (250 c) may be fabricated from sapphire. It ispresently recognized that transparency of sapphire in the visible and inthe near infrared spectrum, as well as its hardness and toughness, makesapphire suitable for operation of the camera-based flow sensor (250)according to the present disclosure in harsh environments, including ina lateral section of an oil well (e.g., Well_1 of FIG. 1 ).

According to an embodiment of the present disclosure, each of the one ormore illuminators of the illuminator system (250 b) may be lightemitting diodes (LEDs) configured to emit a high-brightness light in thevisible or the near infrared spectrum. According to a nonlimitingembodiment, such high-brightness light may include spectrally narrowlight. As used herein, the expression “spectrally narrow” refers to aspectral content at full-width at half-maximum bandwidth in a wavelengthrange from 20 to 100 nm. According to an example embodiment of thepresent disclosure, a near infrared super-luminescent light emittingdiode (NIR SLED) known to a person skilled in the art may be used as aninfrared illuminator of the illuminator system (250 b). According to anonlimiting embodiment, the infrared illuminator may emit light at awavelength between 1500 nm and 1700 nm, e.g. about 1600 nm.

According to an example embodiment of the present disclosure, a visiblesuper-luminescent light emitting diode (visible SLED) known to a personskilled in the art may be used as a visible illuminator of theilluminator system (250 b). According to a nonlimiting embodiment, thevisible illuminator may emit light at any wavelength of the visiblespectrum, including at wavelength corresponding to red, green or bluecolors. As described above, the infrared illuminator of the illuminatorsystem (250 b) may be used for detection of features in oil. On theother hand, the visible illuminator of the illuminator system (250 b)may be used for detection of features in phases other than oil (e.g.,water, gas).

In some cases, it may be advantageous to measure the local fluidvelocity vector V_(FK) at different angular positions about the centeraxis C of the element (220) for derivation of an angular profile of theflow rate. It follows that according to an example embodiment of thepresent disclosure and as shown in FIG. 4B, the camera-based flow sensor(250) may rotate about the center axis C of the element (220). Forexample, FIG. 4B shows the sensor (250), and therefore the camera system(250 a) and the illuminator system (250 b), at an angular position thatis different by an angle θ from the angular position of the sensor (250)shown in FIG. 4A. Such rotation of the sensor (250) about the centeraxis C may be considered as a rotation in the azimuth direction of thelateral portion of the well which therefore allows derivation ofazimuthal profiles of the flow rate.

With continued reference to FIG. 4B, according to an example embodimentof the present disclosure, the rotation of the camera-based sensor (250)may be based on a rotation of the element (220) to which the sensor(250) is rigidly coupled. In such configuration, the element (220),which may be referred to as a nose of the mobile vessel (200 of FIG. 3), may be a rotating part of the mobile vessel. Rotation of the nose(220) may be dependent on or independent from a rotation of the vesselitself (e.g., 210 and 220 rotating in unison). The nose (220) may rotateclockwise and/or counterclockwise to achieve a desired angular positionof the camera-based sensor (250).

FIG. 4C shows a configuration (400 c) of a camera-based flow sensor (400c) according to an embodiment of the present disclosure for simultaneousmeasurement of flow rate at a plurality of angular positions.Measurement of the flow rate at each of the plurality of angularpositions is provided by a camera-based flow sensor similar to thecamera-based flow sensor (250) described above with reference to FIGS.4A and 4B. As can be seen in FIG. 4C, each of the (radial) camera-basedflow sensors (250) is positioned (e.g., fixed) at a different angularposition. Although the example configuration (400 c) of FIG. 4C showsthree flow sensors (250) arranged at different angular positions, inquadrature, other configurations including more or less flow sensors(250) arranged at different angular positions may be envisioned,including, for example, four flow sensors (250) arranged in quadrature.The configuration shown in FIG. 4C may allow simultaneous measurement offlow rate at a plurality of angular positions without requiring any ofthe flow sensors (250) to rotate about the center axis C. If desired,more flexibility (e.g., more angular data points) in measurement may beprovided by (e.g., independently or in unison) rotating the flow sensors(250) in a fashion similar to one described above with reference to FIG.4B (e.g., rotation of nose 220).

FIG. 5A shows details of a cross sectional front view (500 a) of thecamera-based flow sensor (250) according to an embodiment of the presentdisclosure. As shown in FIG. 5A, such cross sectional view (500 a) is ina plane (x, y) that is orthogonal to the center axis, C (not shown inFIG. 5A for clarity purposes). As shown in FIG. 5A, the camera-basedflow sensor (250) may further include a support platform (e.g., base 250f) used for mounting/fixating elements (e.g., 250 a, 250 b, 250 c, 250d, 250 e) into one sensor assembly that may be rigidly fixated/connectedto the element (220) of the mobile vessel (e.g., shown in FIG. 3 ).Further included in the camera-based flow sensor (250) may be athermoelectric cooler (250 e) mounted on, and in contact with, thesupport platform (250 f). In turn, the camera system (250 a) and of theilluminator system (250 b) may be mounted on, and in contact with, thethermoelectric cooler (250 e).

According to an embodiment of the present disclosure, the thermoelectriccooler (250 e) may be used to control temperature of camera system (250a) and of the illuminator system (250 b) for operation in hightemperature conditions as provided in the downhole of a well. Accordingto an embodiment of the present disclosure, the thermoelectric cooler(250 e) may control (cool down) (e.g., different hashed line patternsindicating different temperature control regions/zones of element 250 ein FIG. 5A) from the temperature of the illuminator system (250 b) toallow each of the systems (250 a) and (250 b) to operate within theirrespective safe and stable temperature ranges. Furthermore, if desired,the thermoelectric cooler (250 e) may control temperature of respectivevisible or infrared elements of the camera system (250 a) and theilluminator system (250 b) independently (e.g., infrared cameraindependently from visible camera, and infrared illuminatorindependently from visible illuminator).

With continued reference to FIG. 5A, according to an embodiment of thepresent disclosure, a sensing sequence using the camera-based sensor(250) may include the steps: i) determination of operation/sensingaccording to visible spectrum, infrared spectrum, or both, includingboth in a sequence (e.g., multiplexing) or both simultaneously; ii)based on the determination according to i), activating of thethermoelectric cooler (250 e) to control the temperature of respectivevisible and/or infrared elements of the camera system (250 a) and/or theilluminator system (250 b) to within operating ranges; iii) onceoperating ranges of the temperatures are obtained, based on thedetermination according to i), activate the visible and/or infraredelements of the illuminator system (250 b) thereby emitting (constantpower) light through the window (250 c) into the fluid mixture; and iv)activate the visible and/or infrared elements of the camera system (250a) thereby receiving and capturing images of features in the fluidmixture for completion of the sensing sequence.

Captured image data (e.g., pixels) from the above sensing sequence maybe processed to determine a velocity of the features and deduce avelocity of the fluid based on the velocity of the features. Suchsensing sequence may be performed via a sensor electronic block (e.g.,540 of FIG. 5B later described with further reference to FIG. 7 ) thatmay be local (e.g., part of) to the sensor (250). Processing of thecaptured image data may be performed within same sensor electronicblock, or by a different electronic/processing block that may be part ofthe mobile vessel (e.g., 200 of FIG. 3 ) or located outside the mobilevessel. It should be noted that the above sensing sequence may beadapted for operation in the transmissive mode using the above describedquantum dot illuminators. This may include (simultaneous) injecting ofone or more quantum dot illuminators (e.g., a group of quantum dotilluminators or a quantum dot illuminator group), and recording acorresponding time of injection which can be used, along with a time ofdetection of a frame that includes the injected one or more quantum dotilluminators or group of quantum dot illuminators, the time-of-flight.

With continued reference to FIG. 5A, as described earlier, each of thecamera system (250 a) and the illuminator system (250 b) may includerespective functionalities for operation/sensing in the visible spectrumand/or in the (near) infrared spectrum. For example, the camera system(250) may include a visible camera and an infrared camera schematicallyshown in FIG. 5A as element (250 a) having an optical axis O_(A), and avisible illuminator and an infrared illuminator schematically shown inFIG. 5A as element (250 b) having an optical axis O_(B), wherein O_(A)and O_(B) may be parallel with respect to one another, and substantiallyorthogonal to the plane defining the window (250 c plane x, z)). Itshould be noted that although the optical axis O_(A) and O_(B) shown inFIG. 5A represents the optical axis for the visible/infrared cameras andthe visible/infrared illuminators, such configuration should not beconsidered as limiting the scope of the present disclosure, as otherconfigurations with separate/different optical axes for each of one ormore cameras of the camera system (250 a) and of one or moreilluminators of the illuminator system (250 a) may be envisioned basedon the present teachings.

With further reference to FIG. 5A, according to an example embodiment ofthe present disclosure, the camera system (250 a) may include a dualvisible-infrared imaging sensor and related electronics (250 a 2) whichin combination with a corresponding optical path (250 a 1), defined bythe optical axis O_(A), can (selectively) operate over the visibleand/or infrared spectrum. As known by a person skilled in the art,operation/performance of an imaging sensor may be quantified by itsquantum efficiency response curve as a function of a wavelength. Forexample, FIG. 6 shows a graph representative of a performance of anexample CMOS imaging sensor that may be used as a visible imaging sensorin the camera-based flow sensor according to the present disclosure. Asshown in the graph of FIG. 6 , for a (visible) wavelength range betweenabout 450 nm and 750 nm, the imaging sensor exhibits a quantumefficiency that is equal to, or higher than, 50%. In other words, forsuch wavelength range, the sensor may convert a fraction higher than 50%of the light (photon) energy received by the sensor into electricalenergy. A similar quantum efficiency performance in an infraredwavelength range may be provided for an infrared imaging sensor that maybe used in the camera-based flow sensor according to the presentdisclosure. It should be noted that although a quantum efficiencyperformance of at least 50% may be desirable, such value of theperformance may not be considered as limiting the scope of the presentdisclosure, as lower values (e.g., in a range from about 10% to 50%) ofthe quantum efficiency may be used at the expense of, for example, extrasignal processing routines. Furthermore, in a case where both visibleand infrared sensors are used simultaneously, a corresponding broaderspectral range of the captured images may provide a higher resolutionfor detection of the features, and therefore, lower performance imagingsensors may be possible.

According to an example embodiment of the present disclosure, theilluminator system (250 b) may include a dual visible-infraredilluminator (250 b) that can operate to emit visible and/or infraredlight through an optical path (250 b) defined by the optical axis O_(B).It should be noted that design techniques for configuring each of theelements (250 a) and (250 b) for dual visible and infrared operation areknown in the art and not the subject of the present disclosure. A personskilled in the art will know of many such design techniques, withpreferred implementations based on design goals and limitations,including, for example, cost, performance/resolution, and/or availablephysical space.

Relative positioning/arrangement of the camera system (250 a) and theilluminator system (250 b) of the camera-based flow sensor according tothe present teachings may be a design choice and based on, for example,available space in the element (200) as well as respective size of theelements (250 a) and (250 b). According to a nonlimiting embodiment ofthe present disclosure, the two elements (250 a) and (250 b) may bepositioned so that their respective optical axes O_(A) and O_(B) aredistanced in the x-direction as shown in FIG. 5A. According to anothernonlimiting embodiment, the two elements (250 a) and (250 b) may bepositioned so that their respective optical axes O_(A) and O_(B) aredistanced in the z-direction as shown in the cross sectional side view(500 b) of FIG. 5B, the z-direction being orthogonal to the plane (x, y)of FIG. 5A, or in other words, the z-direction being parallel to thecenter axis, C.

With further reference to cross sectional side view (500 b) of FIG. 5B,the camera-based sensor (250) may further include a sensor electronicblock (540) mounted on the support platform (250 f). Optionally, thesensor electronic block (540) may be mounted on the thermoelectriccooler (250 e) for (individual) control of its operating temperature ina manner similar (e.g., always activated) to the above describedtemperature control of elements (250 a) and (250 b). The sensorelectronic block (540) may include functionality to perform the abovedescribed sensing sequence for either operation in the reflective ortransmissive mode of operation of the camera-based flow sensor (250).Details of the sensor electronic block are provided below with referenceto FIG. 7 for the reflective mode of operation, and with reference toFIG. 9 for the transmissive mode of operation.

FIG. 7 shows a block diagram (700) according to an embodiment of thepresent disclosure of the camera-based flow sensor described above withreference to FIG. 5A and FIG. 5B. As can be seen in FIG. 7 , the blockdiagram (700) includes the sensor electronic block (540) described abovewith reference to FIG. 5B that is configured to control operation of,and receive and/or process data from, the camera system (250 a) and theilluminator system (250 b). A block (710) may interface with the sensorelectronic block (540). According to an example embodiment, the block(710) may be part of the mobile vessel (e.g., 200 of FIG. 3 ) whereinthe camera-based flow meter is integrated/mounted. According to anotherexample embodiment, the block (710) may be part of the camera-based flowmeter such as to provide a standalone sensor. It should be noted thatthe various blocks shown in the block diagram (700) may not necessarilybe interpreted as related to physical distinct blocks/assemblies, ratherrepresentative of different functional blocks for operating thecamera-based flow sensor according to the present disclosure.Accordingly, partitioning of such functional blocks into physicalblocks/assemblies may be based on, for example, a method of use of thecamera-based flow sensor.

With continued reference to FIG. 7 , the block (710) may include a powersupply block (710 a) for provision of power to the block (540), and adata storage/interface block (710 b) that may be used to store datacaptured/generated by the blocks (250 a, 250 b, 540), including forexample, measured flow rates/velocities and related metadata. Accordingto an example embodiment of the present disclosure, the metadata mayinclude, for example, one or more captured images related to a flowvelocity measurement; time stamps of the captured images; and positionaldata, including axial position relative to a length of the downhole andazimuthal position (e.g., angular position of the camera-based flowsensor). Other data and/or metadata may be included depending on aconfiguration of the camera-based sensor (e.g., single/multiple flowsensors, reflective/transmissive mode of operation). According to anexample embodiment, the data storage/interface block (710 b) may be usedby the sensor electronic block (540) to gather information on phasespresent in the fluid mixture at the time of the flow/velocitymeasurement. As noted above, the camera-based flow sensor according tothe present disclosure may use information sensed/gathered by other typeof sensors (e.g., temperature, pressure, composition), which may beprovided via the data storage/interface block (710 b).

With further reference to FIG. 7 , according to an embodiment of thepresent disclosure, the sensor electronic block (540) may include amicrocontroller block (540 a, e.g., implemented via any device known toa person skilled in the art, including a microprocessor and/or a fieldprogrammable gate array FPGA), an image processing block (540 b), acamera electronic block (540 c), a temperature control block (540 d) andan illuminator control block (540 e). According to an example embodimentof the present disclosure, the microcontroller block (540 a) may beconfigured to synchronize all tasks related to the sensing sequence(e.g. steps i) to iv)) described above with reference to FIG. 5A bycontrolling, for example, operation of each of the blocks (540 b, 540 c,540 d, 540 e). For example, the microcontroller block (540 a) mayoptionally interface with block (710 b) to determine phases of fluidpresent and accordingly determining operation/sensing according tovisible spectrum, infrared spectrum, or both; activate thethermoelectric cooler (e.g., 250 f of FIGS. 5A-5B) via the temperaturecontrol block (540 d); activate the visible and/or infrared illuminator(e.g., 250 b) via the illuminator control block (540 e); andactivate/select processing of images in the visible and/or infraredspectrum captured by the camera (e.g., 250 a) via the image processingblock (540 b). It should be noted that under control of the sensorelectronic block (540), a plurality of velocity measurements may beperformed using the camera-based flow sensor according to the presentteachings without input/output from/to the data storage/interface block(710 b). In other words, a plurality of (uncalibrated) velocitymeasurements may be performed and then provided, along withcorresponding time stamps, to the block (710 b) for calibration andinterpretation based on known position/orientation of the sensor by theblock (710 b) at the corresponding time stamps.

Although not shown in FIG. 7 , in some embodiments of the presentdisclosure, the microcontroller block (540 a) may directly interfacewith the camera system (250 a) and/or corresponding camera electronicblock (540 c) to activate operation of the camera system according tothe visible and/or infrared spectrum, and/or to control other relatedtasks (e.g., FIG. 9 later described).

According to an embodiment of the present disclosure, the cameraelectronic block (540 c) may process each pixel in a correspondingvisible/infrared imaging sensor of the camera system (250 a), includingintensity acquisition of each pixel, and send processed pixel data tothe image processing block (540 b). In turn, the image processing block(540 b) may format/arrange the processed pixel data into separate imageframes and process/analyze each of the separate image frames fordetection of one or more features and relative movement of such featuresfrom one frame to the other. Based on the relative movement of featuresdetected in the image frames, the image processing block (540 b) maydeduce a velocity of the features and therefore a measurement of thevelocity of the flow, and provide such measurement (e.g., optionallyalong with above described metadata) to the microcontroller block (540a). It should be noted that video/image processing techniques fordetecting of features and tracking of such features from frame to frameare known in the art and not the subject of the present disclosure. Aperson skilled in the art will know of many such video/image processingtechniques, with preferred implementations based on design goals andlimitations, including, for example, cost, performance/resolution,and/or available processing speed.

FIG. 8A shows details of a cross sectional side view (800 a) of acamera-based flow sensor according to another embodiment of the presentdisclosure that is based on the camera-based flow sensor described abovewith reference to FIG. 5A and FIG. 5B, with additional capability tooperate in the transmissive mode via injection into the fluid mixture ofone or more quantum dot illuminators (880, e.g., as a group of quantumdot illuminators). As shown in FIG. 8A, the camera-based flow sensorincludes a quantum dot illuminator system (810) that includes a storagecompartment (820) for storage of the quantum dot illuminators (880), andan ejection/release mechanism/zone (850) that is configured toeject/release one or more quantum dot illuminators (880) from thestorage compartment (820, reservoir), thereby injecting the one or morequantum dot illuminators (880) into the fluid mixture.

As shown in FIG. 8A, at a time T1, a quantum dot illuminator (880, e.g.,as a group of quantum dot illuminators) is injected into the fluidmixture, which travels along with, and in the direction of, the localfluid velocity vector V_(Fk) towards the (position of the) field of viewof the camera system (250 a). At time T2, the quantum dot illuminator(880) reaches the (position of the) field of view of the camera system(250 a) and is therefore detected/captured by the camera. Atime-of-flight of the quantum dot illuminator (880) can be determinedbased on the time of travel (T2−T1), and the velocity of the quantum dotilluminator (880), and therefore of the fluid mixture, can be determinedfurther based on a distance traveled (labeled as D in FIG. 8A) duringthe time-of-flight. As shown in the configuration (800 b) of FIG. 8B, anincreased accuracy of the velocity can be provided via provision of oneor more additional camera systems (250 a, included in the additionalelement 250′ of FIG. 8B). Such additional one or more camera systems(250 a) may allow to calculate additional time-of-flights, such as forexample, (T3-T2) to cover the distance D′, and (T3−T1) to cover thedistance D+D′, which may be used to provide an averaged velocity of thequantum dot illuminator (880). It should be noted that as describedabove, the time-of-flight may be based on a single injected quantum dotilluminator (880), or a group/cluster of quantum dot illuminators (880)injected into the fluid mixture concurrently (at a same time).

The configurations (800 a) and (800 b) shown in FIG. 8A and FIG. 8B mayallow operation of the camera-based flow sensor according to thereflective (illuminators' back-reflected light) and transmissive(quantum dot illuminators transmitted light) modes. According to anexample embodiment of the present disclosure, as shown in FIG. 8C, thecamera-based flow sensor may be configured for operation solely in thetransmissive mode. FIG. 8C shows details of a cross sectional side view(800 c) of a camera-based flow sensor according to another embodiment ofthe present disclosure that is configured for operation solely in thetransmissive mode. A person skilled in the art will clearly realize thatthe configuration (800 c) of FIG. 8C is based on the configuration (800b) described above with reference to FIG. 8B, but without theilluminator system (250 b).

As described above, the quantum dot illuminator system (810) shown inFIGS. 8A, 8B and 8C may allow operation according to the transmissivemode. Accordingly, the sensor electronic block (840) shown in FIGS. 8A,8B and 8C may include additional functionality to control/synchronizeoperation of the quantum dot illuminator system (810). This is shown inthe block diagram (900) of FIG. 9 , including an additional block (840b) which under control of the microcontroller block (540 a) may controloperation of the quantum dot illuminator system (810), including,preparing for ejection/release of one or more quantum dots (e.g., 880 ofFIG. 8C) by controlling the block (810) to move the one or more quantumdots from the reservoir (e.g., 820 of FIG. 8C) to the ejection/releasemechanism/zone (e.g., 850 of FIG. 8C); and to eject/release bycontrolling the block (810) to immediately (e.g., synchronous to aflag/timestamp) eject/release the one or more quantum dots through theejection/release mechanism/zone. Furthermore, the camera electronicblock (540 c) may include further functionality to detect an increase inintensity acquired by one or more pixels and forward a correspondingflag to the microcontroller block (540 a) as a detection event of aquantum dot illuminator. In turn the microcontroller block (540 a) maycalculate the time-of-flight of the detected quantum dot illuminator forfurther processing/calculation of the velocity (e.g., either by block540 a or through block 710 b). It should be noted that the block diagram(900) includes functionality that support the transmissive mode ofoperation of the configuration shown in FIG. 8C. The same functionalitymay be added to the block diagram (700) described above with referenceto FIG. 7 to support both the reflective and transmissive modes ofoperation of the configuration shown in FIG. 8A and FIG. 8B.

Protrusion of the camera-based flow sensor (e.g., 250 of FIG. 3 ) intothe flow of the fluid mixture may cause undesired perturbations in theflow that may affect measurements/sensing performed by other sensorsthat may be integrated into the mobile vessel. It follows that accordingto an embodiment of the present disclosure the camera-based flow sensormay be retractable into the mobile vessel. This is shown in FIG. 10A,wherein the camera-based flow sensor (250) is shown retracted into aspace within the nose (220) of the mobile vessel (200). In suchconfiguration, the camera-based flow sensor (250) may remain in theretracted position so long flow velocity measurements are not performed.For measurement, the flow meter (250) may be extended outwards the nose(220) in a position as shown in FIG. 3 .

It should be noted that the camera-based flow sensor of the presentteachings may be mounted on any part of the mobile vessel (200),including the main body (210) as shown in FIG. 10B. In suchconfiguration, a different calibration routine may be performed toderive the effective fluid velocity in view of a different flowrestriction imposed in a region of the field of view of the camera.Furthermore, it should be noted that the camera-based flow sensor of thepresent teachings may be mounted on any mobile vessel configured forimmersion in harsh environments such as, for example, a downhole of awell, including the lateral section of the well (e.g., lateral sectionof well_1 shown in FIG. 1 ). In other words, the mobile vessel may notnecessarily be a mobile robot with advanced technologies. Rather, it canbe a simple submersion vessel (1010) as shown in FIG. 10C fitted withthe camera-based flow sensor (250).

A number of embodiments of the disclosure have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the presentdisclosure. Accordingly, other embodiments are within the scope of thefollowing claims.

The examples set forth above are provided to those of ordinary skill inthe art as a complete disclosure and description of how to make and usethe embodiments of the disclosure and are not intended to limit thescope of what the inventor/inventors regard as their disclosure.

Modifications of the above-described modes for carrying out the methodsand systems herein disclosed that are obvious to persons of skill in theart are intended to be within the scope of the following claims. Allpatents and publications mentioned in the specification are indicativeof the levels of skill of those skilled in the art to which thedisclosure pertains. All references cited in this disclosure areincorporated by reference to the same extent as if each reference hadbeen incorporated by reference in its entirety individually.

It is to be understood that the disclosure is not limited to particularmethods or systems, which can, of course, vary. It is also to beunderstood that the terminology used herein is for the purpose ofdescribing particular embodiments only and is not intended to belimiting. As used in this specification and the appended claims, thesingular forms “a,” “an,” and “the” include plural referents unless thecontent clearly dictates otherwise. The term “plurality” includes two ormore referents unless the content clearly dictates otherwise. Unlessdefined otherwise, all technical and scientific terms used herein havethe same meaning as commonly understood by one of ordinary skill in theart to which the disclosure pertains.

1. A system for gathering information about physical properties in alateral section of a well, the system comprising: a mobile vesselconfigured for submersion into a fluid mixture of the lateral section ofthe well; and a camera-based flow sensor attached to the mobile vessel,the camera-based flow sensor comprising: a camera system configured tocapture images in a visible spectrum and in an infrared spectrum; and anilluminator system configured to emit light in the visible spectrum andin the infrared spectrum, wherein the camera-based flow sensor isconfigured to emit light into the fluid mixture and capture images ofback-reflected light from features present in the fluid mixture.
 2. Thesystem according to claim 1, wherein: an image captured by thecamera-based flow sensor is based on activation of the illuminatorsystem and the camera system for operation according to one of thevisible spectrum or the infrared spectrum.
 3. The system according toclaim 1, wherein: an image captured by the camera-based flow sensor isbased on simultaneous activation of the illuminator system and thecamera system for operation according to the visible spectrum and theinfrared spectrum.
 4. The system according to claim 1, wherein: theimages of back-reflected light from the features present in the fluidmixture comprises a sequence of consecutive images, and the camera-basedflow sensor determines a velocity of the fluid mixture based on relativemovement of the features within the sequence of consecutive images. 5.The system according to claim 1, wherein the illuminator systemcomprises: a visible light source that emits a spectrally narrow lightin a wavelength range from 400 nm to 750 nm, and an infrared lightsource that emits light in a near infrared wavelength range near 1600nm.
 6. The system according to claim 5, wherein: the visible lightsource is a super-luminescent light emitting diode (SLED) with aspectral content at full-width at half-maximum bandwidth in a wavelengthrange from 10 nm to 100 nm.
 7. The system according to claim 1, wherein:the mobile vessel comprises a first element having a substantiallytubular shape about a center axis, the first element configured torotate about the center axis, and the camera-based flow sensor includesan enclosure and a window that in combination provide a sealed interiorspace for protection of the camera system and the illuminator system,the enclosure and the window protruding from the first element.
 8. Thesystem according to claim 7, wherein: the enclosure comprises acylindrical shape that is radially attached to the first element.
 9. Thesystem according to claim 8, wherein: respective optical axes of thecamera system and the illuminator system are orthogonal to the centeraxis.
 10. The system according to claim 1, wherein: the camera-basedflow sensor further comprises a thermoelectric cooler system configuredto control a temperature of the camera system independently from atemperature of the illuminator system.
 11. The system according to claim1, wherein: the camera-based flow sensor further comprises a quantum dotilluminator system configured to release one or more quantum dotilluminators into the fluid mixture, and the camera-based flow sensor isfurther configured to capture a first image of light emitted from theone or more quantum dot illuminators.
 12. The system according to claim11, wherein: the camera-based flow sensor determines a velocity of thefluid mixture based on a first time-of-flight of the one or more quantumdot illuminators, and the first time-of-flight is based on a distancebetween a release zone of the quantum dot illuminator system and aposition of a field of view of the camera system, and a time between thecapture of the first image and the release of the one or more quantumdot illuminators.
 13. The system according to claim 12, wherein: thecamera-based flow sensor further comprises an additional camera system,and the camera-based flow sensor is further configured to capture, viathe additional camera system, a second image of light emitted from theone or more quantum dot illuminators.
 14. The system according to claim13, wherein: the camera-based flow sensor further determines thevelocity of the fluid mixture based on a second time-of-flight of theone or more quantum dot illuminators, the second time-of-flight is basedon a distance between the position of the field of view of the camerasystem and a position of a field of view of the additional camerasystem, and a time between the capture of the second image and thecapture of the first image.
 15. The system according to claim 11,wherein: the one or more quantum dot illuminators comprises particles ornanocrystals of a semiconducting material with diameters in a range from2 nm to 10 nm. 16.-19. (canceled)
 20. A camera-based flow sensor,comprising: a camera system configured to capture images in a visiblespectrum and in an infrared spectrum; and an illuminator systemconfigured to emit light in the visible spectrum and in the infraredspectrum, wherein the camera-based flow sensor is configured to emitlight into a fluid mixture and capture images of back-reflected lightfrom features present in the fluid mixture.
 21. (canceled)
 22. A methodfor measuring a flow velocity of a fluid mixture, the method comprising:emitting a light into the fluid mixture; based on the emitting,capturing a sequence of consecutive images of back-reflected light fromfeatures present in the fluid mixture; and based on the capturing,determining the flow velocity based on relative movement of the featureswithin the sequence of consecutive images.
 23. (canceled)